Map number/ID is not embedded in screenshot metadata

When you take a screenshot, the PNG metadata will contain some information like your player name, coordinates, and the name of the level the screenshot was taken in. Normally, both the level's player-facing name and internal ID are shown but in Ring Racers the ID is given as "Unknown" for all maps.

Example screenshot:

The relevant metadata, according to metadata2go.com:

Metadata of an SRB2 screenshot, for reference:

SRB2 is able to successfully embed the map ID into the PNG metadata, which leads me to believe this is a regression